OTTAWA — The Harper government is defending a Conservative senator who is under investigation for an alleged ethical lapse, touting his reputation as a “tireless” defender of the rights of victims of crime.

Sen. Pierre-Hugues Boisvenu is facing the ethics probe over his own revelations in a published media report that he had intervened with the Senate administration to negotiate improved job benefits for his girlfriend, who previously worked in his office.

The Senate ethics officer confirmed the investigation, in response to a complaint that Boisvenu allegedly violated ethics rules that prevent senators from furthering private interests or influencing the decision of another person to further those interests.

Despite the new investigation, Boisvenu was prominently featured at a Conservative government event in Montreal Friday and was thanked by Justice Minister Peter MacKay for participating in efforts to help draft a new bill of rights for Canadian victims of crime.

“Senator Boisvenu is a tireless supporter of the victims of crime, which is why he participated in today’s consultations,” said MacKay’s spokesman Sean Phelan. “The senator’s office has stated he will fully cooperate with the ethics commissioner’s investigation. All of today’s consultation participants are focused on how to better entrench the rights of victims into law at the federal level.”

MacKay’s office declined to answer a question about whether he would continue to stage public events with Boisvenu, appointed to the Senate by Prime Minister Stephen Harper in 2010.

Other senators appointed by Harper who are facing ongoing RCMP probes over spending scandals, Mike Duffy, Pamela Wallin and Patrick Brazeau, have resigned from the Conservative caucus, while former Liberal Mac Harb has retired and paid back more than $230,000 worth of expenses.

Boisvenu paid back about $900 in housing expenses in March 2013 that he said were mistakenly claimed. He had also faced questions about thousands of dollars of housing claims in the Ottawa region, but an internal Senate review determined he was eligible to declare his Sherbrooke home, shared with his wife, as a primary residence.

Boisvenu became a prominent victims’ rights advocate in Quebec after his daughter was murdered in 2002 by a 27-year-old man who was on probation. Boisvenu also lost a second daughter in a road accident in 2005.

The office of the Senate ethics officer, Lyse Ricard, declined to provide details about the investigation, explaining that the conflict of interest code for senators requires confidentiality for its investigations.

Liberal Sen. Celine Hervieux-Payette prompted the probe when she wrote to the ethics officer in June, noting that Boisvenu had previously been warned about hiring his girlfriend in his office.

“My only hope is that the investigation won’t take forever,” said Liberal Sen. Céline Hervieux-Payette, in an interview.

“Each time these things drag on for months, the entire institution pays the price.”

Hervieux-Payette wrote in her June letter that Boisvenu didn’t respond to warnings from the ethics officer until a media report from Montreal newspaper La Presse revealed that he was having a romantic relationship with a staffer, Isabelle Lapointe, who was working in his office as an assistant.

“It was public pressure that actually forced him to comply with the recommendations,” she wrote.

After Lapointe left the office, Hervieux-Payette alleged that Boisvenu made another mistake by trying to improve her job benefits in a new position with the Senate administration.

“Senator Boisvenu has failed to distinguish between his role as an employer and his stats as a Senator prohibited from intervening with the Senate administration to secure financial benefits for a ‘family member,’ in accordance with basic ethical standards.”

Boisvenu’s office declined to comment, saying only that he would co-operate with the investigation.